//变量
export const pi=3.14
export const pi2=3.1444
//方法
function sum(a,b){
    return a+b

}
//类
class person{

    constructor(name,age){
        this.name=name;
        this.age=age
    }
    sayHello(){
        console.log(`hello,my name is ${this.name},i am ${this.age} years old`);
    }
}